That sounds as if it is a brain.
Another answer:
It is the Thalamus.
The thalamus consists of two lateral masses of neural tissue that are joined by a narrow isthmus of neural tissue called the intermediate mass.
It is some fibers of grey mater that form anterior and posterior commissures which connect right and left side of spinal cord and along this specific area most fibers corss spinal cord to opposite side.
Gray commissure
The corpus callosum is a bridge of nervous tissue that connects the two cerebral hemispheres, allowing communication between the right and left sides of the brain.It is not the pons which is at the top of the spinal cord. It connects the cord to the brain. Pons means bridge.
the corpus callosum
A structure called the corpus callosum connects the left and right sides of the brain.
It is located in lower right and left sides of the spinal cord channel.
The central canal of the spinal cord runs down the center of spinal cord from top to bottom and allows cerebrospinal fluid to circulate. The part of the spinal cord directly around the central canal is the gray commissure. This is what connects the two halves of the spinal cord and allows signals to travel between the two sides.
A rhombus has four congruent sides. The angles don't matter, but if they're right angles, then the rhombus is a square.
The spinal cord passes through the cervical vertebrae, and the spinal nerves pass through the transverse foramina on both left and right sides.
It's the balanced distribution of body part on both sides a the spinal cord in vertebrates, or on both sides of the thorax in insects. People have an arm and a leg on both sides of the spinal cord.
arrow
The arched bridge of nervous tissue that connects the two cerebral hemispheres, allowing communication between the right and left sides of the brain.
The sides, doesn't matter but the length is usually the bottom and top line, while the width is usually the left and right sides.
corpus callosum